1. Field of the Invention
The present invention relates to a motion estimation apparatus and a method thereof, and, more particularly, to a motion estimation apparatus and a method thereof capable of detecting scrolling text and graphic data in a horizontal direction on a screen.
2. Description of the Related Art
There exist the interlaced scan mode and the progressive scan mode for scan modes for a video display device. The interlaced scan mode is used for general TVs and so on, and refers to a mode that, when one image is displayed, divides one frame image into two fields and sequentially displays the two fields one after the other, whereas the progressive scan mode is used for computer monitors, digital TVs, and so on, and refers to a mode that displays at a time entire frames with one image frame processed as a unit frame just like a film is projected on a screen.
As more video display devices of progressive scan mode are used and, at the same time, the necessity of data exchanges among devices using different scan modes grows, the importance is placed more than ever before on the interlaced-to-progressive conversion (IPC) method that converts the interlaced scan mode into the progressive scan mode. Therefore, IPC methods having a far more enhanced performance are required to obtain images of better quality.
There exist diverse methods for interlaced-to-progressive conversions. As basic methods, there are an intra-field IPC method that inserts average data of two-line data between two lines of a current field to implement a new field, and an inter-field IPC method having no motion compensation that inserts between lines of a current field average data of data ahead of and behind the current field to implement one frame. Such IPC methods are easily implemented, but cannot achieve a satisfactory image quality. Accordingly, a motion-compensated IPC method has been proposed that divides an image into plural blocks with respect to time-continuous field data with reference to current field data, obtains motions for the respective blocks, and interpolates a current frame image with reference to vectors of the motions. A motion-adaptive IPC method has been also proposed that estimates the extent of motions and interpolates frames based on the motions, and so on. Such IPC methods can obtain an image quality better than the basic methods, but have relatively more complicated hardware.
However, the IPC methods are not suitable for displays of text or graphic data such as news, programs, stock prices, whether, and so on, with horizontal scrolling at the bottom of a screen, and so on. That is, due to the characteristics of scrolling text or graphic data, in case that the intra-field IPC method or the intra-field IPC method is used, text in interpolated images is not clearly displayed, and displays broken letters on many occasions. Further, in case of scrolling text or graphic data, because plural lines move on the screen in the horizontal direction at a certain speed, image interpolations can be easily implemented if there is information of whether scrolling text or graphic data exists and a scrolling speed, so that excellent image interpolations in terms of performance or speed become possible without the use of a complicated algorithm such as the motion-compensated IPC method or the motion-adaptive IPC method.
Therefore, a motion estimation apparatus and a method applicable to IPC methods and the like become necessary for detecting whether text or graphic data scrolling in the horizontal direction of a screen exists and proving information necessary for image interpolations.